This invention relates to a novel emulsifier composition having an excellent improvement effect for starch-containing foods. Due to their function and safety, mono- and diglycerides are widely used as emulsifiers in the present food processing industry. The function of the emulsifiers differs, depending on the purity, appearance, physical and chemical properties, and the types of fatty acid of which they are constituted.
In the case of starch containing food, such emulsifiers are required to react well, particularly with starch, to obtain a complex with the starch. Monoglyceride having a saturated fatty acid moiety of 14 to 18 carbon atoms is known to meet this requirement.
In the case of using mono- and diglycerides in the fat phase, there is no restriction on the physical properties of the mono- and diglycerides because they can be dissolved into fat. However, in case of starch-containing food, it is desirable to use a monoglyceride in the aqueous phase in order to obtain a starch-complexing improvement effect.
In these circumstances or where the monoglyceride is mixed with the raw material in powdered form, physical appearance, physical and chemical properties such as the crystalline form of the monoglyceride and, the surface condition thereof, etc. have a significant bearing on this function.
Monoglycerides are known to be polymorphic and are classified according to sub-.alpha., .alpha., .beta.' and .beta.-crystalline forms which are arranged in order of increasing melting points. The .beta.-crystalline form is the most stable thermodynamically and monoglycerides have always been marketed in the .beta.-crystalline form.
The reason why the .alpha.-crystalline form is more effective in the aqueous phase can be assumed to be because of a difference in hydrophilicity. As a means of obtaining the .alpha.-crystalline form, there is a so-called conjoined crystal method employing the combined use of saturated fatty acid monoglyceride and fatty acid propyleneglycol ester (J. Am. Oil., Chem 40, 725, (1963)), or a method comprising forming a dispersion in water at a temperature below the melting point of the monoglyceride. However, each of these methods has disadvantages, such as a small content of monoglyceride, difficulty in temperature control or in preservation properties.
From these standpoints, it has long been desired to obtain a monoglyceride having the stable .beta.-crystalline form and which, at the same time, exhibits good functional properties. Various methods have been considered to improve hydrophilic properties by increasing the surface area of crystals. As these means, there is a method whereby minute crystals of monoglyceride are obtained by recrystallization using a polar solvent (Japanese patent publication No. SHO 50-34613) and a method whereby an aqueous dispersion of the .beta.-crystalline form is obtained by adding a stabilizer into a water-dispersion of monoglyceride or a method whereby a dry powdered monoglyceride is obtained by adding hydrophilic binders into a water-dispersion of monoglyceride (Japanese patent publication No. SHO 44-26900). Each of these methods have excellent improvement effects. However, with respect to obtaining powdered monoglyceride, the methods are disadvantageous because they tend to be expensive from the standpoint of production efficiency, and a product in paste form is inferior in handling, preservation and stability. Therefore, the development of a more simplified process has long been desired for obtaining a powdered monoglyceride which is effective in the aqueous phase. As a result of intensive research work in consideration of these shortcomings, the present inventors have discovered a novel emulsifier composition which provides good quality improvement effects to starch containing food, and which is easier to handle, less expensive, withstands longer preservation time and is stable.